Climatic control especially for animal buildings

ABSTRACT

The present invention involves a climatic control for ventilation of the roof of buildings, particularly animal buildings. The system involves a thermostatic switch which discriminates between winter and summer positions. In the winter position it operates a control including a sensing variable resistor, which may for example change its resistance with change of sunlight, temperature, wind velocity, wind direction or evaporation. In the summer it connects with a timer switch which at night maintains the venting louvers open, unless they are closed by a rain switch. In the day the timer switch maintains the venting louvers closed or nearly closed. This is applied particularly to an animal building, preferably of the type which has venting louvers in a sloping roof directed toward the south.

United States Patent [191 Wenger CLIMATIC CONTROL ESPECIALLY FOR ANIMALBUILDINGS [76] Inventor: Caleb M. Wenger, RD. 1,

Quarryville, Pa. 17566 22 Filed: Dec.ll, 1972 21 Appl. No.: 314,017

Related U.S. Application Data [63] Continuation-impart of Ser No.250,986, May 8,

1972, abandoned.

[52] U.S. Cl 236/46, 1 65/16, 236/49, 318/471 [5l] Int. Cl. F24f 7/02,HOlr 29/00 [58] Field of Search .[236/49, 46; 318/471; 200/6104;340/235; 165/16 [56] References Cited UNITED STATES PATENTS 2,499,5443/1950 Vancil 236/49 X 3,329,341 7/1967 Jones 236/49 X [4 Apr.2, 1974Primary ExaminerWilliam E. Wayner Attorney, Agent, or Firm-.lacks0n,Jackson and Chovanes [57] ABSTRACT The present invention involves aclimatic control for ventilation of the roof of buildings, particularlyanimal buildings. The system involves a thermostatic switch whichdiscriminates between winter and summer positions. In the winterposition it operates a control including a sensing variable resistor,which may for example change its resistance with change of sunlight,temperature, wind velocity, wind direction or evaporation. In the summerit connects with a timer switch which at night maintains the ventinglouvers open, unless they are closed by a rain switch. in the day thetimer switch maintains the venting louvers closed or nearly closed. Thisis applied particularly to an animal building, preferably of the typewhich has venting louvers in a sloping roof directed toward the south.

7 Claims, 5 Drawing Figures PAIENIED PR 2W 801' 008 sum 1 or 3PATENTEDAPR 2W4 3 8011 D08 SHEET 3 OF 3 l CLIMATIC CONTROL ESPECIALLYFOR ANIMAL BUILDINGS This application is a continuation-in-part ofapplication Ser. No. 250,986, filed May 8, 1972, now abandoned, forCLIMATIC CONTROL ESPECIALLY FOR ANIMAL BUILDINGS.

The present invention is a climatic control, preferably for venting andotherwise affecting an animal building by opening and closing louvers inthe roof, in response to summer and winter, the presence or absence ofsunlight, or a critical temperature, a wind of a particular direction, awind of a particular velocity, and the presence or absence ofprecipitation, herein referred to generically as rain.

The invention is preferably applied to ridge roof buildings (calledcoupled rafter roofs in the Encyclopedia Britannica) in which one orboth sides of the sloping roof has louvers. The side having louvers willpreferably be oriented toward the south and will preferably more steeplyslope than the other side of the sloping roof from the ridge asexplained more in detail in US. Pat. No. 3,556,055 issued Jan. 19, I971for BUILDING FOR ANIMALS and United States patent application Ser. No.104,976, filed Jan. 8, 1971 for BUILDING FOR ANIMALS, incorporatedherein by reference.

The invention involves a thermostatic switch which disposes the controlcircuit in winter mode or summer mode of operation. In the winter modeof operation a special electronic circuit including a sensing resistor,transistor switching units which produce an output depending upon theresistance of the sensor resistor, a relay responding to the output anda servomechanism such as a reversing motor and drum which operates thelouver covers are actuated. In the summer mode of operation a timerswitch is utilized which discriminates between night and day. In thenight mode of summer operation the venting louvers are opened unlessclosed by a rain switch, all operating through suitable relays andservomechanism. In the day mode of operation the venting louvers areclosed through a suitable relay and servomechanism.

In the winter mode of operation a controlled delay is interposed by anelectronic timer, having a timer capacitor and timer resistors in seriesand in parallel relation to the timer capacitor, and controlling thevoltage which operates the transistor switching unit.

In the drawings I have shown a preferred embodiment of the invention.

FIG. 1 is an illustrative electrical diagram of the power pack used forthe control of the invention.

FIG. 2 is an illustrative electrical diagram of the winter control unitused in the invention.

FIG. 2a is an illustrative electrical diagram of the thermostatic switchwhich discriminates between winter and summer, the timer switch forsummer operation, the rain switch and the relays and servomechanismassociated therewith.

FIG. 3 is a diagram showing the drum and cables controlled by the relay.

FIG. 4 is a fragmentary vertical section showing the animal building andthe louvers of the invention and the application of the control to thelouver covers.

The device includes in its main parts a power pack 10, a thermostaticswitch 120, a sensor, preferably a photoresistor 11, a time delaynetwork 12, a transistor switching device 13, a relay 14, a timer switch124 and a rain switch 132.

FIG. 1 shows the power pack for operation of the low voltage controlsand relays.

FIG. 2 shows the control unit for winter operation, and FIG. 2a showsthe thermostatic switch, timer switch and rain switch which makeautomatic operation in the summer possible.

It will be evident that different sensors can be substituted for thesensor 11 (instead of the photoresistor); for example, it can bereplaced by a temperature sensitive resistor or a wind pressure switchor a resistor which varies the resistance with wind pressure, or a winddirection indicator. The sensor can be exposed at any convenient placewhere it will respond to the presence or absence of the sun or othercontrolling quantity.

Taking the current from suitable AC power leads and 21, FIG. 1, thevoltage is stepped down by transformer 22 and it energizes a full waverectifier 23, suitably a silicon rectifier, having four rectifier unitspositioned with their cathodes 24 in sequence around the branches of therectifier network, which may be designated 25, 26, 27 and 28.

Between branches 28 and is terminal 30 to which one side of thetransformer secondary is connected to terminal 31 between branches 26and 27. Rectified current is taken off at terminal 32 (plus) betweenbranches 25 and 26 and at terminal 33 between branches 27 and 28 and therectified current supplies leads 34 and 35 (which may be grounded),shunted by filtering capacitor 36.

FIG. 2a shows part of the circuit for control as to whether it shalloperate in the winter mode or in the summer mode. The thermostaticswitch 120 which is connected to the terminal 34 in FIG. I has a winterposition in which it closes contact 121 and a summer position in whichit closes contact 122. When it is in the winter position, it energizesterminal 34' in FIG. 2, which will not be described.

In FIG. 2, connected to lead 34, in series therewith, is the resistor ofthe sensor unit 11 just described, and also timer network 12 which isconnected across to ground. The timer network involves a potentiometerhaving resistors and 41 adjustable in unison, the resistor 40 beingconnected to the opposite side of the sensor resistor from the powerlead 34, and the resistor 41 being connected in a branch 42 of a groupof parallel branches across to the ground and in series with theresistor 40.

Another branch 43 is in series with the resistor 40 but in parallel withthe branch 42 and contains capacitor 44 whose charge and dischargecontrols the time delay.

Also in parallel with the branches 42 and 43 but not in series with theresistor 40 is branch 45 which includes fixed resistor 46 connected toground. In parallel with branch 42 and 43 and in series with resistor 40is branch 47 having resistors 48 and 50.

The transistor switching unit 13 includes three transistors 60, 61 and62, which may be of general purpose switching transistors, of whichtransistors and 62 are PNP type and transistor 61 is of the NPN type.Transistors 60 and 61 are the main switching transistors and transistor62 matches the impedance of the relay. The transistor 60 has its emitterconnected through resistor 63 to the power lead 34 and has its collectorconnected to an intermediate point between resistors 48 and 50. Thetransistor 61 has its emitter connected to ground through the power lead35 and its base connected to the intermediate point between resistors 48and 50. The base of transistor 60 is connected to power lead 34 throughresistors 64 and 65 which are in series and are connected to thecollector of transistor 61.

Thus in each of the switching transistors 60 and 61, on the input sideconnection is made to the collector of the PNP transistor and to thebase of the NPN transistor and on the output side connection is made tothe collector of the NPN transistor and to the base of the PNPtransistor. The emitter of the PNP transistor is connected to the highside of the power source, and the emitter of the NPN transistor isconnected to the low side of the power source.

Transistor 62 has its base connected intermediate between resistors 64and 65, has its emitter connected to the high side 34 of the power lineand its collector connected to one side of the coil 66 of relay 14, theother side of which is connected to power lead 35 and ground.

Relay 14 has two switching circuits 67 and 68 and energization of therelay closes one of these circuits and opens the other of these circuitsand vice versa. An electric motor 70 which may be of the induction typehas two opposed field coils 71 and 72, respectively in the circuit 67 or68 in series with limit switches 73 and 74 to be described, which are ofthe type in which one is always open when the other is closed. Theintermediate point between the field coil 71 and 72 is connected to thepower lead 21 and to ground, and the high side of the circuits 67 and 68is connected to the power lead In the summer position as seen in FIG.2a, when contact 122 is closed timer switch 124 is energized by coil 126connected between power leads 20 and 21. The timer switch closes contact128 for night operation and contact 130 for day operation. In nightoperation it energizes rain switch 132 which closes contact 134 if theweather is fair and closes contact 136 if there is any precipitation. lfcontact 134 is closed for fair weather operation, relay coil 138 isenergized across to ground 35 and this closes relay contacts 140 in avent coil circuit across between power lead 20 and power lead 21 throughvent coil 71 and limit switch 73 which is described elsewhere, and whichwill be closed if vent coil 71 is operative to maintain the ventinglouvers open.

If there is rain, contact 136 is closed, which energizes relay 142closing relay contacts 144 which energizes vent coil 72 connected acrossbetween power leads 20 and 21 if the limit switch 74 is closed, as itwill be if the venting louvers are in the position in which vent coil 72is operative.

If the timer switch 124 is in daytime operation it closes contact 130,energizing relay coil 144 across to ground, which closes relay contacts146 and energizes vent coil 72 between power leads 20 and 21, providinglimit switch 74 is closed, as it will be if the venting louvers are intheposition in which vent coil 72 is operative. This closes the ventinglouvers or nearly closes them as desired.

MODE OF OPERATlON The thermostatic switch 120 determines whether theoperation is on the winter or the summer mode.

If the operation is on the winter mode, then what immediately followsapplies.

When the sensing unit is dark (when a photoresistor of selenium type isused), it will be of high resistance and therefore it actuates thevoltage divider provided by the timer network in such a way that thetimer is subjected to a low voltage. This particular mode forming partof the overall winter mode discharges any residual charge on thecapacitor such that the timer comes to a steady state and remains stableuntil such time that the sensor conditions change. The voltage output ofthe timer is monitored by the transistor switching unit 13. Under thiscondition the minimum threshold voltage of the switching unit isrealized; hence, the switch is in an off mode, and the relay is notenergized. When sun comes to the sensor 11, through filter 11', itvastly reduces its resistance and vastly increases the voltage on thevoltage divider and the timer network 12. With the high voltage increaseon the timer network, the capacitor will charge until such time that theoutput of the timer network again being monitored by the switching unitpasses a switch threshold voltage and thereby triggers the switchingunit into an on mode and therefore triggers the relay on, which startsthe electric motor 70. The time delay on it equal to the time delay offand equals the time which it takes for the charge or discharge of thecapacitor to adjust from one mode to another.

Adjusting the values of the potentiometer resistors 40 and 41 changesthe time delay. This increase of the resistors 40 and 41 lengthens thetime delay, and decrease of the resistors 40 and 41 reduces the timedelay.

In case instead of a photoresistor the sensing resistor 11 is athermistor or other temperature measuring device the functioning will bethe same. In case the sensing unit is a wind pressure indicator whichhas two modes of operation, one a high resistor and one a low resistoras accomplished for example by mechanical switching in the windindicator, the method will be the same. Similarly, the sensor 11 can bea wind direction indicator which by mechanical switching therein reducesor increases the resistance of the sensor 11 and exerts control.

While in the invention l have shown a timer which delays the actuationof the transistor switching unit so that the device will not respond toa momentary change in sunlight, temperature or wind characteristics, itwill be evident that in the broadest aspects of the invention the changein response of the sensing unit may directly operate the transistorsensing unit without the delay.

If the thermostatic switch 120 determines to operate on the summer modeof operation, then the timer switch 124, which is continuously keepingtime, has its appropriate contact energized. If it determines that nightoperation prevails, it opens the venting louvers by relay 138 and ventcoil 71 unless the rain switch 132 indicates precipitation in which caserelay 142 and relay contacts 144 energize vent coil 72 to close theventing louvers. 1f the timer switch 124 determines that daytimeoperation is appropriate, then relay coil 144 is energized to closerelay contacts 146 and to energize vent coil 72 to close the ventinglouvers.

FIG. 3 shows diagrammatically a rotatable drum which has a cable 81wound thereon at one end and a cable 82 wound thereon on the other end,the winding of the cable 81 and 82 being in opposite directions so thatone winds and one unwinds. This can be one cable if desired.

The drum is driven by the reversing motor 70 as previously described.

The cables 81 and 82 branch at 86 and 87 on one end and at 88 and 90 onthe other end, the branches running over suitable pulleys 91 and beingconnected at 92 in an operative way to the ventilating devices to openthem or close them depending on whether cable 81 or 82 is pulling. Thus,the device opens or closes the ventilating louvers by pulling on cable81 or 82 as desired. It will be evident that the cables cut off themotor in either direction by limit switches 73 or 74. These limitswitches are capable of being adjusted to shut off the motor when theventilators are partially open or completely open or partially orcompletely closed as desired. The limit switches limit the function ofthe motor in either direction and when one limit switch is open, theswitch in the other direction is closed.

APPLICATION OF CONTROL DEVICE TO BARNS AND THE LIKE The presentinvention is a further development on the subject matter involved inWenger et al, US. application Ser. No. 104,976 for BUILDING FOR ANI-MALS, filed Jan. 8, 1971, now pending in the U5. Patent Office, andWenger US. Pat. No. 3,556,055, issued Jan. 19,- I971 on application Ser.No. 809,234, filed Mar. 21, 1969 for BUILDING FOR ANIMALS, both ofwhich, along with the previously mentioned US. application Ser. No.146,043, parent to this, are incorporated herein by reference. Thisapplication is a continuation-in-part of application Ser. No. 250,986,now abandoned.

It is especially intended to be used in a building for animals such asfound in the first mentioned application, and this also can be used withother buildings for animals which have the capability of control ofsunlight and/or ventilation and/or water shedding, that is the closingof openings in the roof if there is likelihood of precipitation.

Where the control device in the winter mode is based on the sunlight,this can for example be used to admit large amounts of sunlight duringsunny periods in the cold season, and to close the openings, partiallyor entirely, when the sun is not shining.

When the sensing device which applies to open and shut the louversduring the winter mode is based on temperature, it can, for example, beused to open ventilating access during periods of comparative heatduring that mode, and close this partly or entirely when the temperatureis less warm. Also, in winter it can close the louvers when weather ofinclement type is encountered if the louvers are desired to be openedduring the less severe cold.

Both these features of sun response and temperature response can becombined in one setup, so that there can be further regulation based onsunlight on the colder part of the winter mode, and with the addition,for example, of a manual switch to put the thermostatic control intooperation of temperature control during the warmer part of that wintermode.

It will be evident that all this, as well as the alreadydescribedoperation in the summer mode, can be done especially for example on thedevice of the above mentioned application Ser. No. 104,976 that is nowpending.

Especially in some places where the wind is especially likely to beirregular and to be disturbing factor in the regulation of the wellbeing of the animals in the building, as, for example, Where mountainconditions may control prevailing winds, the wind direction or pressureregulator may be available and pretinent for use, especially in thewinter mode. This and the other controls are especially important ineliminating or reducing the tendency toward fouling of the air in viewof the presence of the large number of animals in a comparatively smallspace. The wind control can, for example, be used to close the louversof a building like that in the pending application, when a wind iscoming fron an unusual or undesirable direction irregularly to theplacement of the building, as, for example when the wind is continuingto blow in in strength into the louvers themselves and then into thebuilding. This would be especially important in the cooler weather.

In what is said above, it is not intended to limit the application ofthe invention to a building of the type and orientation described in thepatent and application Ser. No. 104,976, but it also applies to animalbuildings of other types and orientations which have louvers or othermeans of admitting sun or air or both or water vapor and the like andother such things.

EXAMPLE OF APPLICATION TO AN ANIMAL BUILDING In FIG. 4 the building hasa ridge roof having a greater roof portion running to a ridge 101 and alesser roof portion 102. The roof is supported by roof beams 103 onwhich beams or nailers 104 extend longitudinally of the roof. At theridge 101 the greater roof section 100 is above the lesser roof section102 to provide a vent 105 which can be used to ventilate the interior ofthe building. The permanent roof sections are made by securing sheets106 of metal or the like to the nailers. At suitable points along thegreater roof section there may be a sky light. The lesser roof sectionis preferably disposed toward the south and has at suitable pointsrunning transverse to the slope of the roof louvers 107 having covers108 preferably of metal or a suitable sheet material, convenientlyhinged at 109 and closing with respect to the lower louver in closedposition at l 10, controlled by cables 81 and 82 suitably fastened toeach louver at 92 as already described. The vent 105 is preferablyclosed by a vent cover 11 1 hinged at 112, suitably controlled manually.

In the specific embodiment of the circuit of FIGS. 1 and 2, thefollowing dimensions of components are desirable for a specificembodiment.

Output of Power Pack Filtering Capacitor Comparative Size ofPotentiometer l 2 volts I500 microfarads It will be understood thatwhile I have often described the louvers herein as ventilating louvers,they may at appropriate times in appropriate weahter also have theeffect of admitting or shutting out sunlight, and especially so when theroof in which they are located slopes downward more or less toward thesouth, as would be most usual. Rain may also be shut out.

It will also be understood that while I have described certain controls,modes or the like by terms like winter and summer, the actual thing forwhich they will be adjusted is for colder conditions on the one hand andwarmer on the other, and in accordance with what is required in thebuilding involved. Thus, conceivably the so-called summer mode might ina given climate with a given building go into operation in a mild partof winter, and the so-called winter mode might in a given climate with agiven building go into operation in a cold part of summer, and it woulddepend upon the adjustment and the weather what would be operating at agiven time in spring or fall.

It is somewhat similar as to controls or modes or the like which I havedenominated as night or day. The particular hours that would actually beinvolved would depend upon how the timer was set to get the bestresults. For example, the timer would most usually in a given case beset so as to include some early part of morning and possibly also somelate part of afternoon, when the sun was especially low and ineffective,in the so-called night operation.

In view of my invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of myinvention without copying the mechanism shown, and I therefore claim allsuch insofar as they fallwithin the reasonable spirit and scope of myclaims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a control mechanism for controlling ventilation, a thermostaticswitch having a winter mode and a summer mode, a sensing element havinga variable resistor connected to the thermostatic switch in the wintermode, responding to an electrical quantity which dominates the control,a transistor switching mechanism energized and connected to the sensingresistor in the winter mode to respond to its change in resistance, arelay connected to the output side of the transistor switchingmechanism, a series of ventilators, means for energizing the relay andwhen this occurs to operate the ventilators, a timer switch energized inthe summer mode, operatively connected to a rain switch, means foropening the ventilators in the summer mode if the timer switch indicatesnight and the rain switch indicates fair weather, means for closing theventilators in the summer mode if the timer switch indicates night andthe rain switch indicates precipitation, and means for closing theventilators in the summer mode if the timer switch indicates day.

2. In a mechanism of claim 1, having for the winter mode interposedelectrically between the sensing resistor and the transistor switchingmechanism, a time delay network for delayingthe response of thetransistor switching mechanism, the transistor switching mechanismincluding a PNP junction transistor and a NPN junction transistor, theinput side of the switching mechanism being connected with the collectorof the PNP junction transistor and the base of the PNP junctiontransistor being also connected to the input, the output side of thetransistor switching mechanism being connected with the collector of theNPN junction transistor and the base of the PNP junction transistorbeing connected also to the output, the respective emitters of thetransistors being connected to the high and low side of the powersource.

3. A mechanism of claim 2, in which the time delay network includes atime delay capacitor and time delay resistors, a first time delayresistor being connected in series with the capacitor between thesensing resistor and the input of the switching transistors, and asecond time delay resistor being connected in parallel with a condenserand in series with the first time delay resistor.

4. A mechanism of claim 3, in which the first and second time delayresistors are part of a potentiometer which includes means forincreasing and reducing their resistance in unison.

5. A mechanism of claim 4, in which the time delay network also includesa third time delay resistor in parallel with the first time delayresistors and with the capacitor.

6. A mechanism of claim 5, in which the time delay network also includesa fourth time delay resistor and a fifth time delay resistor which arein series with the first time delay resistor and in parallel with thecapacitor, and the second time delay resistor, the input of theswitching transistors being connected between th fourth and fifth timedelay resistors.

7. A mechanism of claim 6, in which the switching transistor mechanismincludes a first PNP junction transistor, a second NPN junctiontransistor and a third PNP junction transistor, and first, second andthird switching resistors, the first transistor being connected with itscollector on the input side, its emitter connected through the firstswitching resistor to the high side of the power source and its baseconnected through the second switching resistor to the base of the thirdswitching resistor, the second switching transistor having its baseconnected to the input, its emitter connected to the grounded side ofthe power source, and its collector connected to the second switchingresistor and through it to the base of the third switching transistor,the third switching resistor being connected be-' tween the base of thethird switching transistor and the high side of the power source, theemitter of the third switching resistor being connected to the high sideof the power source, and the collector of the third switchingtransistor, being connected to one side of the relay.

1. In a control mechanism for controlling ventilation, a thermostaticswitch having a winter mode and a summer mode, a sensing element havinga variable resistor connected to the thermostatic switch in the wintermode, responding to an electrical quantity which dominates the control,a transistor switching mechanism energized and connected to the sensingresistor in the winter mode to respond to its change in resistance, arelay connected to the output side of the transistor switchingmechanism, a series of ventilators, means for energizing the relay andwhen this occurs to operate the ventilators, a timer switch energized inthe summer mode, operatively connected to a rain switch, means foropening the ventilators in the summer mode if the timer switch indicatEsnight and the rain switch indicates fair weather, means for closing theventilators in the summer mode if the timer switch indicates night andthe rain switch indicates precipitation, and means for closing theventilators in the summer mode if the timer switch indicates day.
 2. Ina mechanism of claim 1, having for the winter mode interposedelectrically between the sensing resistor and the transistor switchingmechanism, a time delay network for delaying the response of thetransistor switching mechanism, the transistor switching mechanismincluding a PNP junction transistor and a NPN junction transistor, theinput side of the switching mechanism being connected with the collectorof the PNP junction transistor and the base of the PNP junctiontransistor being also connected to the input, the output side of thetransistor switching mechanism being connected with the collector of theNPN junction transistor and the base of the PNP junction transistorbeing connected also to the output, the respective emitters of thetransistors being connected to the high and low side of the powersource.
 3. A mechanism of claim 2, in which the time delay networkincludes a time delay capacitor and time delay resistors, a first timedelay resistor being connected in series with the capacitor between thesensing resistor and the input of the switching transistors, and asecond time delay resistor being connected in parallel with a condenserand in series with the first time delay resistor.
 4. A mechanism ofclaim 3, in which the first and second time delay resistors are part ofa potentiometer which includes means for increasing and reducing theirresistance in unison.
 5. A mechanism of claim 4, in which the time delaynetwork also includes a third time delay resistor in parallel with thefirst time delay resistors and with the capacitor.
 6. A mechanism ofclaim 5, in which the time delay network also includes a fourth timedelay resistor and a fifth time delay resistor which are in series withthe first time delay resistor and in parallel with the capacitor, andthe second time delay resistor, the input of the switching transistorsbeing connected between the fourth and fifth time delay resistors.
 7. Amechanism of claim 6, in which the switching transistor mechanismincludes a first PNP junction transistor, a second NPN junctiontransistor and a third PNP junction transistor, and first, second andthird switching resistors, the first transistor being connected with itscollector on the input side, its emitter connected through the firstswitching resistor to the high side of the power source and its baseconnected through the second switching resistor to the base of the thirdswitching resistor, the second switching transistor having its baseconnected to the input, its emitter connected to the grounded side ofthe power source, and its collector connected to the second switchingresistor and through it to the base of the third switching transistor,the third switching resistor being connected between the base of thethird switching transistor and the high side of the power source, theemitter of the third switching resistor being connected to the high sideof the power source, and the collector of the third switchingtransistor, being connected to one side of the relay.